前言

在mysql中有一个默认的数据表information_schema,information_schema这张数据表保存了MySQL服务器所有数据库的信息。如数据库名,数据库的表,表栏的数据类型与访问权限等。

再简单点,这台MySQL服务器上,到底有哪些数据库、各个数据库有哪些表,每张表的字段类型是什么,各个数据库要什么权限才能访问,等等信息都保存在information_schema表里面,所以请勿删改此表。整理了一份328页MySQLPDF文档

代码

1,切换数据库

use information_schema;

2,查看数据库使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ ;

3,查看表使用大小

select concat(round(sum(data_length/1024/1024),2),’MB’) as data from tables where table_schema=’DB_Name’ and table_name=’Table_Name’;

网上找的一个,亲测可用:

  • 先进去MySQL自带管理库:information_schema

  • 然后查询 data_length,index_length

  • 你自己的数据库名:dbname

  • 你自己的表名:tablename
    mysql> use information_schema;
    Database changed
    mysql> select data_length,index_length
    -> from tables where
    -> table_schema='dbname'
    -> and table_name = 'tablename';
    +-------------+--------------+
    | data_length | index_length |
    +-------------+--------------+
    | 166379520 | 235782144 |
    +-------------+--------------+
    row in set (0.02 sec)
    mysql> select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB,
    -> concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
    -> from tables where
    -> table_schema='dbname'
    -> and table_name = 'tablename';
    +----------------+-----------------+
    | data_length_MB | index_length_MB |
    +----------------+-----------------+
    | 158.67MB | 224.86MB |
    +----------------+-----------------+
    row in set (0.03 sec)

    1.查看所有数据库容量大小

select
table_schema as '数据库',
sum(table_rows) as '记录数',
sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',
sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'
from information_schema.tables
group by table_schema
order by sum(data_length) desc, sum(index_length) desc;

2.查看所有数据库各表容量大小

select
table_schema as '数据库',
table_name as '表名',
table_rows as '记录数',
truncate(data_length/1024/1024, 2) as '数据容量(MB)',
truncate(index_length/1024/1024, 2) as '索引容量(MB)'
from information_schema.tables
order by data_length desc, index_length desc;

3.查看指定数据库容量大小

例:查看mysql库容量大小

select
table_schema as '数据库',
sum(table_rows) as '记录数',
sum(truncate(data_length/1024/1024, 2)) as '数据容量(MB)',
sum(truncate(index_length/1024/1024, 2)) as '索引容量(MB)'
from information_schema.tables
where table_schema='mysql';

4.查看指定数据库各表容量大小

例:查看mysql库各表容量大小

select
table_schema as '数据库',
table_name as '表名',
table_rows as '记录数',
truncate(data_length/1024/1024, 2) as '数据容量(MB)',
truncate(index_length/1024/1024, 2) as '索引容量(MB)'
from information_schema.tables
where table_schema='mysql'
order by data_length desc, index_length desc;

select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB, concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
from tables 
where table_schema='passport' and table_name='tb_user_info';

-- 569.98MB 141.98MB

select concat(round(sum(data_length/1024/1024),2),'MB') as data_length_MB, concat(round(sum(index_length/1024/1024),2),'MB') as index_length_MB
from tables
where table_schema='passport_v2' and table_name='tb_user_info';

-- 2128.94MB 285.00MB 整理了一份328页MySQLPDF文档